I think the performance of the 6mm and 6.5mm versions seem to be better than other calibers. The saami chamber specs are better than the older calibers and ruger won't use match-type chambers for the .300 win mag (mk248 for example) . That's one reason I got better performance from the krieger barrel even before it was broken in. Higher velocity too. Another thing I noticed is the windage adjustment in the scope was centered in its travel . The ruger factory barrel required several MOA of windage to zero. The quality just wasn't there. Like I said, in retrospect I don't think this rifle was a good purchase once a good barrel, trigger, ergonomic grip, and reliability items such as a more durable bolt handle are purchased to make the rifle work The 6mm and 6.5mm may not need a new barrel right away so that's the way to go vs. magnum variant.